Salts Flashcards
how can a soluble salt be prepared with an insoluble reactant? (3)
by reacting an acid with:
a metal
a metal oxide
a carbonate
why do chemists avoid reacting metals and acids?
-what is the alternative?
- reaction between metals and acids produces flammable hydrogen,
- reacting a metal oxide or a metal carbonate with an acid.
what are salt names comprised of?
-what are they?
two parts
- first is the metal, metal oxide or metal carbonate
- second is the acid
what do different acids produce? (3)
-in reference to hydrochloric acid, nitric acid and sulfuric acid
- hydrochloric acid produces chloride salts
- nitric acid produces nitrate salts
- sulfuric acid produces sulfate salts
Method to making a soluble salt from an acid and an insoluble reactant: (5)
- Add some dilute hydrochloric acid to a beaker.
- Add powdered insoluble reactant to some acid in a beaker, one spatula at a time, stirring to mix. The mixture will effervesce.
- Continue adding powder until some unreacted powder is left over - it is in excess.
- Filter the mixture in the beaker to remove the excess powder.
- Allow the water in the solution to evaporate (by heating and/or leaving for a few days) to obtain pure dry crystals of the salt.
Notes on each step of making a salt: (3)
- To make sure all of the acid has reacted, add the excess of the solid reactant.
- Filtering removes the unreacted insoluble reactant from the salt solution.
- As the acid is all used up and the insoluble reactant has been removed, this only leaves the salt and water. Therefore evaporating the water leaves the pure salt.
how can a soluble salt be prepared by reacting an acid with a soluble reactant?
-the soluble reactant is usually a dilute solution of an alkali
what is a substance’s solubility?
a measure of the maximum mass that will dissolve in a given volume of a solvent, at a particular temperature
discuss the solubility of a substance using terms such as ‘high and low solubilities’ (2)
- substances that are very soluble have high solubilities.
- substances that are insoluble or sparingly soluble (almost none dissolves) have low solubilities.
common soluble ionic compounds: (2)
- all common sodium, potassium and ammonium salts
- all nitrates
soluble and insoluble chlorides: (3)
soluble:
- most common chlorides
insoluble:
- silver chloride
- lead chloride
soluble and insoluble sulfates: (4)
soluble:
- most common sulfates
insoluble:
- lead sulfate
- barium sulfate
- calcium sulfate
soluble and insoluble carbonate: (4)
soluble:
- Sodium carbonate
- potassium carbonate
- ammonium carbonate
insoluble:
-most common carbonates
soluble and insoluble hydroxides: (4)
soluble:
- sodium hydroxide
- potassium hydroxide
- ammonium hydroxide
insoluble:
-most common hydroxides
what is a precipitate?
-and what is the reaction that produces them called?
an insoluble product that forms when two solutions are mixed and react together
- precipitation reaction.
what is crucial for a precipitation reaction formula?
-why?
state symbols
-without them, we would not be able to distinguish between the precipitate and the other products from the reaction
how can the formation of a precipitate be predicted? (3)
by using solubility rules
- if the products meet the ‘soluble’ rules in the left hand column, no precipitate will form
- if at least one product meets the ‘insoluble’ rule in the right hand column, a precipitate will form
how could you determine suitable solutions to form precipitates?
All nitrates and all sodium salts are soluble. a given precipitate XY can be produced by mixing together solutions of:
X nitrate
sodium Y
where ‘X’ is the intended first part of the compound and ‘Y’ is the second
outline method for making a pure, dry sample of an insoluble salt: (4)
1- Mix together two suitable solutions (see above).
2- Use filtration to separate the precipitate as a residue from the solution.
3- Wash the precipitate th distilled water while it is in the filter funnel.
4- Leave the washed precipitate aside or in a warm oven to dry.
reasons for each step for making a pure, dry sample of an insoluble salt. (2)
- filtration separates insoluble substances from liquids and solutions.
- precipitate is insoluble in water, so any remaining contaminating solution can be removed by washing it with distilled water.
